Anesthesia by n-alkanes not consistent with the Meyer-Overton hypothesis: determinations of the solubilities of alkanes in saline and various lipids.

Abstract

Because deviations from the Meyer-Overton rule may provide insights into the attributes of the anesthetic site of action, we characterized the solubility of the n-alkanes in various hydrophobic solvents (n-tetradecane, olive oil, n-octanol, and lecithin) as well as saline using variations on standard techniques. Increasing alkane chain length correlated with a decrease in solubility in saline and an increase in solubility in the hydrophobic solvents. The product of solubility in the hydrophobic solvents x the partial pressure (in atmospheres) required to produce anesthesia (i.e., the Meyer-Overton rule) did not produce a constant for any one of these solvents. The means and standard deviations for the products were: tetradecane, 65 +/- 103; olive oil, 33 +/- 63; n-octanol, 64 +/- 129; and lecithin, 16 +/- 26. Thus, our data suggest that the n-alkanes (especially those longer than n-heptane) do not follow the Meyer-Overton rule.